Conventionally, a three-dimensional measuring method that uses the principle of a stereoview using plural CCD cameras is known. According to the conventional technique, measuring points need to be matched among images recorded from different directions, and the processing of these images is complex and ambiguous.
FIG. 7 is a schematic configuration diagram of a three-dimensional measuring apparatus that is devised to solve the above conventional problem. A three-dimensional measuring apparatus 100 rotates a rotating cylinder 33 via a gear 31 that is rotated by a motor 30, thereby rotating mirrors 34 and 35 fitted to the front end of the rotating cylinder 33. With this arrangement, a camera 32 records a circular streak image 36 at a measured point 37. FIG. 8 is a schematic configuration diagram of a three-dimensional measuring apparatus according to another method. A three-dimensional measuring apparatus 200 rotates a rotating cylinder 42 via a gear 41 using a motor (not shown), thereby rotating a reflector 43 fitted to the front end of the rotating cylinder 42 with an angle. With this arrangement, a camera 40 records a circular streak image 45 of a measured point 44. By appropriately using the three-dimensional measuring apparatuses 100 and 200 according to a distance to a measuring point, a satisfactory three-dimensional measurement can be carried out when the number of measuring points is small and when the moving speed of the measuring points is slow. The three-dimensional measuring apparatus 100 is granted as Japanese Patent No. 3346662.
However, when the moving speed of the measuring points is fast, a streak image of the measuring points becomes spiral as shown in FIG. 9. In this spiral moving streak, a size variation and a pitch of a spiral streak correspond to three-dimensional velocity information. When this relation can be analyzed, three components of positions and three components of velocity can be obtained at the same time. However, according to the conventional apparatus, it is difficult to analyze overlapped streaks in the case that the number of measuring points is large.
A circular streak can be approximately analyzed by rotating a system at a sufficiently faster speed than the moving speed of the measuring points. However, an accurate analysis of a spiral image without approximation is desired.
In the light of the above problems, it is an object of the present invention to provide a three-dimensional measuring apparatus that can efficiently analyze a three-dimensional image by simultaneously recording a circular streak image and a straight-line streak image at a measured point, even when a large number of circular streak images are present.